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We have many options when it comes to how we drink water, given the large range of consumer products available, and Australia’s high standards of tap water.

But which option is the smartest choice from an environmental perspective?

According to the waste management hierarchy, the best option is one that avoids waste altogether. Recyclable options are less preferable, and landfill disposal the worst of all.

For water bottles, this suggests that keeping and reusing the same bottle is always best. It’s certainly preferable to single-use bottles, even if these are recyclable.

Of course, it’s hardly revolutionary to point out that single-use plastic bottles are a bad way to drink water on environmental grounds. Ditching bottled water in favour of tap water is a very straightforward decision.

However, choosing what reusable bottle to drink it out of is a far more complex question. This requires us to consider the whole “life cycle” of the bottle.

Cycle of life

A 2012 Italian life-cycle study confirmed that reusable glass or plastic bottles are usually more eco-friendly than single-use PET plastic bottles.

However, it also found that heavy glass bottles have higher environmental impacts than single-use PET bottles if the distance to refill them was more than 150km.

Granted, you’re unlikely ever to find yourself more than 150km from the nearest drinking tap. But this highlights the importance of considering how a product will be used, as well as what it is made of.

What are the reusable options?

Metal bottles are among the most durable, but also require lots of resources to make.Flickr CC

Steel and aluminium options shared the highest environmental impacts from materials and production, due to material and production intensity, combined with the higher mass of the metal bottles, for the same number of uses among the options. The polypropylene bottle performed the best.

Polypropylene bottles are also arguably better suited to our lifestyles. They are lighter and more flexible than glass or metal, making them easier to take to the gym, the office, or out and about.

The flip side of this, however, is that metal and glass bottles may be more robust and last longer, so their impacts may be diluted with prolonged use – as long as you don’t lose them or replace them too soon.

Health considerations are an important factor for many people too, especially in light of new research about the presence of plastic particles in drinking water.

Other considerations aside, is may even be best to simply buy a single-use PET plastic water bottle and then reuse it a bunch of times. They are lighter than most purpose-designed reusable bottles, but still long-lasting. And when they do come to the end of their useful life, they are more easily recycled than many other types of plastic.

Sure, you won’t look very aspirational, but depending on how many uses you get (as you approach the same number of uses as other options), you could be doing your bit for the environment.

Maintaining reusable options

There are a few things to bear in mind to ensure that reusable bottles produce as little waste as possible.

Refill from the tap, as opposed to using water coolers or other bottled water that can come from many kilometres away, requiring packaging and distribution. Unsurprisingly, tap water has the lowest environmental impacts of all the options.

Clean your bottle thoroughly, to keep it hygienic for longer and avoid having to replace grotty bottles. While cleaning does add to the environmental impact, this effect is minor in comparison to the material impacts of buying new bottles – as we have confirmed in the case of reusable coffee cups.

The verdict

To reduce your environmental impacts of a drink of water, reusing a bottle, whether a designer bottle or a single-use bottle you use time and again, makes the most sense from a life-cycle, waste and litter perspective.

The maintenance of your reusable container is also key, to make sure you get as many uses as you can out of it, even if you create minor additional environmental impacts to do so.

Ultimately, drinking directly from a tap or water fountain is an even better shout, if you have that option. Apart from the benefit of staying hydrated, you will reduce your impacts on our planet.

Two years ago, New Zealanders were shocked when contaminated drinking water sickened more than 5,000 people in the small town of Havelock North, with a population of 14,000. A government inquiry found that sheep faeces were the likely source of bacterial pathogens, which entered an aquifer when heavy rain flooded surrounding farmland.

A second phase of the inquiry identified six principles of international drinking water security that had been bypassed. Had they been followed, the drinking water contamination would have been prevented or greatly reduced.

Here, I ask if the approach recommended by the Havelock North inquiry to prevent drinking water contamination can be extended to reduce the impacts of nutrient contamination of freshwater ecosystems.

An important lesson from the Havelock North inquiry is that sometimes there is no recipe – no easy list of steps or rules we can take to work through a problem. Following existing rules resulted in a public health disaster. Instead, practitioners need to follow principles, and be mindful that rules can have exceptions.

For freshwater, New Zealand has a similar problem with a lack of clear actionable rules, and I’ve mapped a direct link between the six principles of drinking water security and corresponding principles for managing nutrient impacts in freshwater.

Six principles for freshwater

Of the six principles of drinking water safety, the first is perhaps the most obvious: drinking water safety deserves a “high standard of care”. Similarly, freshwater nutrient impact management should reflect a duty of care that mirrors the scale of impacts. Our most pristine freshwater, like Lake Taupo, and water on the verge of tipping into nearly irreversible degradation, deserve the greatest effort and care.

Second, drinking water safety follows a clear logic from the starting point: “protecting the integrity of source water is paramount”. For nutrient impact management in freshwater, we must reverse this and focus on a more forensic analysis along flowpaths to the source of excess nutrients entering water. Our current approach of using estimates of sources is not convincing when tracers could point to sources in the same way DNA can help identify who was at a crime scene. We must link impacts to sources.

Third, drinking water safety demands “multiple barriers to contamination”. For freshwater, we’re better off taking a similar but different approach – maximising sequential reductions of contamination. There are at least three main opportunities, including farm management, improving drains and riparian vegetation, and enhancing and restoring wetlands. If each is 50% effective at reducing contaminants reaching waterways, the three are as good as a single barrier that reduces contamination by 90%. The 50% reductions are likely to be much more achievable and cost effective.

Managing hot spots and hot moments

The fourth principle of drinking water safety was perhaps the most dramatic failure in the Havelock North drinking water crisis: “change precedes contamination”. Despite a storm and flood reaching areas of known risk for contaminating the water supply, there were no steps in place to detect changing conditions that breached the water supply’s classification as “secure” and therefore safe.

A similar, but inverted principle can keep nutrients on farm, where we want them, and keep them out of our water. Almost all processes that lead to nutrient excess and mobilisation, as well as its subsequent removal, occur in hot spots and hot moments.

This concept means that when we look, we find that roughly 90% of excess nutrients come from less than 10% of the land area, or events that represent less than 10% of time. We can identify these hot spots and hot moments, and classify them into a system of control points that are managed to limit nutrient contamination of freshwater.

These schemes involved government investment of between NZ$70 million and NZ$80 million to “buy out” a proportion of nutrients reaching the lakes. This cost seems unworkable across the entire nation. Will farmers or taxpayers own this cost, or is there any way to pass it on to investors in new, higher-value land use that reduces nutrient loss to freshwater? A successful example of shifting to higher value has been conversions from sheep and beef farming to vineyards.

As yet, the ownership of water has made headlines, but remains largely unclear outside Taupo and Rotorua when it comes to nutrient contaminants. Consideration of taxing the use of our best water could be much more sensible with a clearer framework of ownership for both water and the impacts of contaminants.

The final principle of drinking water safety is to “apply preventative risk management”. This is a scaled approach that involves thinking ahead of problems to assess risks that can be mitigated at each barrier to contamination.

For nutrient management in water, a principled approach has to start with the basic fact that water flows and must be managed within catchments. From this standpoint, New Zealand has a good case for leading internationally, because regional councils govern the environment based on catchment boundaries.

Within catchments we still have a great deal of work to do. This involves understanding how lag effects can lead to a legacy of excess nutrients. We need to manage whole catchments by understanding, monitoring and managing current and future impacts in the entire interconnected system.

If we can focus on these principles, government, industry, researchers, NGOs and the concerned public can build understanding and consensus together, enabling progress towards halting and reversing the declining health and quality of our rivers and lakes.

Every year Australia’s councils contest the academy awards of the water industry: the Best Tasting Tap Water in Australia. Entrants compete on clarity and colour as well as taste and odour.

This week the NSW/ACT representative will be selected to go on to compete against other state winners in October for the coveted Australian crown. (As in Eurovision, the previous winner hosts the final, so it will be held in Toowoomba, which swept the competition last year with its Mt Kynock Water Treatment Plant vintage.)

It’s a not-so-serious business (apart from bragging rights and a nice trophy, the Australian winner will go to an international competition in the US next year) but it raises an interesting question. All tap water has its own tang, imparted by the source, the plumbing and any treatments. How do you think the water coming out of your tap will go?

What makes water taste good?

The odour of tap water is strongly linked to its taste. No surprises there – the combination of taste and odour is well established.

One of the most common complaints about tap water taste and odour involves chlorine, which is an essential disinfectant used around the world. Chlorine might have an offensive smell, but it is a major weapon against pathogens spreading in our water supplies. Areas with very old and corroded pipes might add more chlorine to counter the risk of microbial contamination entering the system.

Chlorine is highly volatile and you might particularly notice this smell when you run a hot shower. If you want to enjoy drinking water without the chlorine taste or smell, boil it slowly for several minutes. That will remove much of the chlorine. (And then put it in a container in the refrigerator to get much more appealing ice-cold water.)

The taste test

The competition, run by the Water Industry Operators Association of Australia, uses “blind” testing, so the judges do not know the source. All samples need to be at room temperature. The testers use a testing wheel to rate attributes including sweet, sour, salty and bitter.

Water Industry Operators Association

The water will also be judged on clarity, colour, odour and “mouthfeel”. Perhaps the most obvious mouthfeel character of water is effervescence or “sparkling bubbles”, something that consumers will pay plenty for in bottles sourced from exotic-sounding locations.

Hard vs soft

These qualities often reflect water’s origins, which affects aspects like its mineral content. Groundwater generally has a higher mineral content, particularly from areas of limestone rich in calcium and magnesium carbonates. This is called “hard” water.

Water with high levels of hardness may be frustrating when you wash your hands as it can stop a soapy lather forming. Very hard water might also have a salty taste. Hard water can create other issues, such as imparting an unusual flavour in tea and causing a build-up of scale minerals in hot water appliances and water pipes.

The opposite of hard water is “soft” water. This is often from water supplies fed by stored rainfall, which generally contains very dilute sodium chloride (also known as table salt; it’s largely responsible for making seawater salty).

If you live close to the coast and have a tank collecting runoff from your roof you will probably have more salt in your water. You might not actually taste the salt, but you may notice a metallic tang from corrosion of the roof, tank and plumbing triggered by the salt.

Water supplied by rainwater tanks can provide odd tastes and odours. This can be the first sign of a major problem, and you should always investigate the source. Dead animals in the tanks and accumulated vegetation from overhanging trees can be unwelcome tank water quality hazards. It is worth remembering that homes using rainwater tanks often do not treat or disinfect the water before consumption.

A sulphur taste and odour can also occur in some water supplies. This is often termed “rotten-egg gas”, and is caused by hydrogen sulphide. Similar to chlorine, its odour might be detected when running a hot shower. The source of sulphur can be from the water supply geology or from the decay of organic matter.

More and more of Australia’s water supply is highly treated by the local or regional water industry. We have increasing populations and a possibly drying climate. Some areas have a relatively natural supply of high-quality raw water from very clean catchments and storages. Melbourne, Brisbane and Sydney and many locations across Tasmania are fortunate to have very clean and mostly natural water supplies. Other places, like Alice Springs or Perth, rely heavily on treated groundwater.

Desalination has also emerged as a major new water supply source over the last 20 years. It is often used only when lack of rainfall depletes natural water storage, but it is a permanent factor in Perth’s water supply.

It will be a major victory for the Australian water industry if the winning water sample comes from a recycled water supply, particularly if the source includes some component of recycled sewage!

Drinking recycled sewage is a very confronting topic. But what many people don’t realise is that we already rely on recycled sewage in many Australian water supplies. Even in Australia’s biggest city, Sydney, it is an important part of the water supply. This is because many large towns discharge their treated sewage into the catchment rivers that supply the city.

But Perth is now looking to recycle all of its treated sewage. At the time of writing, the city’s water storages were at a low 35.3%. Cape Town’s reserves, by comparison, are at a critical low of 23.5% – but Perth was close to that point just a year ago when it was down to 24.8%.

Perth has been progressively “drought-proofing” itself by diversifying the city water supply. River flow and storage in dams accounts for only 10% of this supply. Desalination and groundwater extraction provide about 90% of the city’s supply. Only about 10% of Perth’s sewage is recycled, through advanced treatment and replenishment into its groundwater supplies.

So how is treated sewage being indirectly reused?

There is, however, indirect reuse when water is drawn from rivers into which recycled sewage is discharged upstream. For instance, the catchment of Sydney’s giant Warragamba Dam has a population of about 116,000 people. This includes the large settlements of Goulburn, Lithgow, Moss Vale, Mittagong and Bowral. These communities discharge their treated sewage into the catchment rivers.

Several large towns discharge treated sewage into rivers supplying Warragamba Dam, which holds 80% of Sydney’s water reserves.popejon2/flickr, CC BY-NC-ND

The New South Wales Environment Protection Authority regulates these discharges, which form a small part of the total annual catchment inflow to the dam. Such recycling of sewage is termed “indirect potable reuse”.

Residents in some parts of northwestern Sydney also drink water that is partly supplied by another form of indirect reuse of treated sewage. The North Richmond Water Filtration Plant extracts and treats water drawn directly from the Hawkesbury-Nepean River. A major contributor to the river flow is treated sewage discharged from upstream treatment plants.

These include plants in the Blue Mountains (Winmalee), St Marys, Penrith, Wallacia, and West Camden. The largest individual discharge of treated sewage to the river in recent weeks is from St Marys Advanced Water Recycling Plant, one of the biggest in Australia. This plant uses advanced membrane technology to produce highly treated effluent before it is discharged into the river.

St
Marys Advanced Water Recycling Plant, one of the biggest in Australia, treats sewage and discharges the water into the Hawkesbury-Nepean River.Ian Wright, Author provided

Available data are limited, but in the very low river flows in the recent dry summer I estimate that treated sewage comprised almost 32% of the Hawkesbury-Nepean flow in the North Richmond area for the first week of January. The water is highly treated at the Sydney Water-owned North Richmond plant to ensure it meets Australian drinking water guidelines.

Paying for desalination while water goes to waste

However, most of Sydney’s sewage is not recycled at all. Three massive coastal treatment plants (at North Head, Bondi and Malabar) serve the majority of Sydney’s population. These three plants discharge nearly 1,000 million litres (1,000ML) of primary treated sewage into the ocean every day. That is roughly an Olympic pool of sewage dumped in the ocean every four minutes!

Perhaps if Sydney was as chronically short of water as Perth there would be plans to recycle more of its sewage. Instead, Sydney has adopted desalination as a “new” source of drinking water, rather than treating larger volumes of sewage for any form of potable reuse.

Sydney’s desalination plant sits idle about 10 kilometres south of the Malabar treatment plant. It has a capacity for supplying 250ML a day. Even though it isn’t supplying water now, it is very expensive. In 2017, the privately owned plant, sitting on standby, charged Sydney Water A$194 million.

Only when Sydney’s storages fall below the trigger of 60% will the plant supply drinking water. With storages at 76.5%, the plant will not operate for a while.

As Cape Town counts down to “day zero” and the prospect of its taps being turned off, there have inevitably been questions about whether the same fate might befall a major Australian city. The most striking parallels have been drawn with Perth – unsurprisingly, given its drying climate, rising evaporation rates (which increase consumption and reduce water yields) and growing population.

So is Perth really running out of water? The answer depends on what type of water is being considered, and what constitutes “running out”.

When faced with this question most people think of drinking water, which is of course essential for household use.

It often ignores non-potable groundwater that is heavily relied upon in Perth to irrigate gardens, lawns, ovals, golf courses and market gardens. This water is also used by light and heavy industry, as well as being crucial to the health of wetlands and vegetation across the coastal plain.

Lake Jualbup in Perth’s western suburbs showing periods of low and high water level. Photos by Geoffrey Dean.saveourjewel.org, Author provided

Perth’s drinking water supplies are largely safe, thanks to early investment in the use of groundwater and in technologies such as desalination. But somewhat ironically, as this recent book chapter explains, the future supply of lower-quality water for irrigation and to support ecosystems looks far less assured.

The overall effect is that soils and vegetation are often dry, meaning that rainfall will be lost to evapotranspiration rather than running off into rivers and dams, or recharging underground aquifers.

At the same time, Perth has made major changes to its drinking water supply. The city now relies chiefly on groundwater and desalination rather than dams. For a variety of reasons, drinking water use per person has declined, most notably since the early 2000s when sprinkler restrictions were introduced. Some have switched to self-supply sources such as backyard bores, so for them total water use may even have increased.

Perth’s trends in runoff, population, and water supply.Water Corporation

Since the late 1970s, Perth has increasingly used groundwater rather than dam water. Seawater desalination has also grown to almost half of total supply. Even more recently Perth began trialling a groundwater replenishment scheme to recharge aquifers with treated wastewater.

With the declines in rainfall and streamflow predicted to continue, water security will continue to be an important policy issue over the next few decades. Although both are much more expensive than dam water, desalination and groundwater replenishment look set to secure Perth’s drinking supply, because seawater is virtually unlimited, and wastewater availability increases in line with the city’s growth.

Why are non-drinking water supplies less secure?

Boosting drinking water supplies with desalination or groundwater replenishment is unlikely to resolve the pressures on non-potable supplies. To understand why, it is necessary to understand Perth’s unusual hydrology.

Most of Perth is built on permeable sand dunes, which can soak up even the heaviest rainfall. This allows runoff from roofs and roads to be directed into nearby soak wells and absorption basins.

About 70% of local road runoff and half of roof runoff already recharges the shallow unconfined aquifer, because it is the cheapest way to dispose of excess water in areas with sandy soils. As well as reducing discharge costs, this practice helps to ensure that bores do not run dry in summer.

Perth also has large main drains that are designed to lower groundwater levels in swampy areas and prevent inundation. Some of these waters could be redirected into the aquifer where there is a suitable site.

Investigations have also shown that the quality of treated wastewater can be greatly improved when infiltrated through the yellow sands into the limestone aquifer in the western part of Perth. It is suitable for irrigation after a few weeks’ residence within the aquifer.

Without these kinds of measures, local governments will struggle to water parks and sports ovals, to protect Perth’s remaining wetlands, and to safeguard the trees that help keep us cool.

So while drinking water supplies for an affluent city like Perth are reasonably secure, our vital non-drinking water supplies need to be augmented using some of the water we currently discharge into the ocean. As Perth gets even hotter and drier, and green spaces and wetlands are needed to provide much-needed cooling, we can no longer afford to let any water go to waste.

Two cities on opposing continents, Santiago
and Cape Town, have been brought to their knees by events at opposing ends of the climate spectrum: flood and drought.

The taps ran dry for Santiago’s 5 million inhabitants in early 2017, due to contamination of supplies by a massive rainfall event. And now Cape Town is heading towards “day zero” on May 11, after which residents will have to collect their drinking water from distribution points.

In many of these places governments have tried to hedge their bets by turning to increasingly expensive and energy-ravenous ways to ensure supply, such as desalination plants and bulk water transfers. These two elements have come together in Victoria with the pumping of desalinated water 150km from a treatment plant at Wonthaggi, on the coast, to the Cardinia Reservoir, which is 167m above sea level.

But while providing clean water is a non-negotiable necessity, these strategies also risk delivering a blowout in greenhouse emissions.

Water pressure

Climate change puts many new pressures on water quality. Besides the effects of floods and droughts, temperature increases can boost evaporation and promote the growth of toxic algae, while catchments can be contaminated by bushfires.

At the height of the Millennium Drought, household water savings and restrictions lowered volumes in sewers (by up to 40% in Brisbane, for example). The resulting increase in salt concentrations put extra pressure on wastewater treatment and reclamation..

The energy needed to pump, treat, distribute and heat water – and then to convey, pump, reclaim or discharge it as effluent, and to move biosolids – is often overlooked. Many blueprints for zero-carbon cities underplay or neglect entirely the carbon footprint of water supply and sewage treatment.

Some analyses only consider the energy footprint of domestic water heating, rather than the water sector as a whole – which is rather like trying to calculate the carbon footprint of the livestock industry by only looking at cooking.

Yet the growing challenge of delivering a reliable and safe water supply means that energy use is growing. The United States, for example, experienced a 39% increase in electricity usage for drinking water supply and treatment, and a 74% increase for wastewater treatment over the period 1996-2013, in spite of improvements in energy efficiency.

As climate change puts yet more pressure on water infrastructure, responses such as desalination plants and long-distance piping threaten to add even more to this energy burden. The water industry will increasingly be both a contributor to and a casualty of climate change.

How much energy individual utilities are actually using, either in Australia or worldwide, will vary widely according to the source of supply – such as rivers, groundwater or mountain dams – and whether gravity feeds are possible for freshwater and sewage (Melbourne shapes up well here, for example, whereas the Gold Coast doesn’t), as well as factors such as the level of treatment, and whether or not measures such as desalination or bulk transfers are in place.

Desalination plants: great for providing water, not so great for saving electricity.Moondyne/Wikimedia Commons, CC BY-SA

One option would be for water facilities to take themselves at least partly “off-grid”, by installing large amounts of solar panels, onsite wind turbines, or Tesla-style batteries (a few plants also harness biogas). Treatment plants are not exactly bereft of flat surfaces – such as roofs, grounds or even ponds – an opportunity seized upon by South Australian Water.

But this is a large undertaking, and the alternative – waiting for the grid itself to become largely based on renewables – will take a long time.

A 2012 study found large variations in pump efficiency between water facilities in different local authorities across Australia. Clearly there is untapped scope for collaboration and knowledge-sharing in our water sector, as is done in Spain and Germany, where water utilities have integrated with municipal waste services, and in the United States, where the water and power sectors have gone into partnership in many places.

The developing world

Climate change and population growth are seriously affecting cities in middle-band and developing countries, and the overall outlook is grim. Many places, such as Mexico City, already have serious water contamination problems. Indeed, in developing nations these problems are worsened by existing water quality issues. Only one-third of wastewater is treated to secondary standard in Asia, less than half of that in Latin America and the Caribbean, and a minute amount in Africa.

The transfer of know-how to these places is critical to reaching clean energy transitions. Nations making the energy transition – especially China, the world’s largest greenhouse emitter – need to take just as much care to ensure they avoid a carbon blowout as they transition to clean water too.

Just as in the electricity sector, carbon pricing can potentially provide a valuable incentive for utilities to improve their environmental performance. If utilities were monitored on the amount of electricity used per kilolitre of water processed, and then rewarded (or penalised) accordingly, it would encourage the entire sector to up its game, from water supply all the way through to sewage treatment.

Water is a must for city-dwellers – a fact that Cape Town’s officials are now nervously contemplating. It would be helpful for the industry to participate in the strategic planning and land-use debates that affect its energy budgets, and for its emissions (and emissions reductions) to be measured accurately.

In this way the water industry can become an influential participant in decarbonising our cities, rather than just a passive player.

This article is based on a journal article (in press) co-authored by David Smith, former water quality manager for South East Water, Melbourne.